1. Field of the Invention
The present invention relates to a method and a control apparatus for self diagnosis and, more particularly, to a method and a control apparatus for self diagnosis suitable for use in such information processing apparatus as a data recorder having a mechanical portion.
2. Description of the Prior Art
It is known that some information processing, instrumentation, or control apparatus or systems have a self diagnostic capability. The self diagnostic capability of a data recorder, for example, includes an initial test to be performed when the data recorder is powered on, error indication, alarming, and error data storage in a regular operation, and various tests in a maintenance operation, among others.
Self diagnosis as generally referred to points at the diagnostic operations to be performed in the regular run of the apparatus as mentioned above, with emphasis placed on error detection. It sometimes can happen that one of the apparatus's functional portions which is used only once in a long while, one year for example, is found defective just before use. With a conventional data recorder, for example, it is a general practice to provide no capability of checking the entire recorder system including its infrequently used functional portion for a failure or no dedicated self diagnostic mode. However, in the field of instrumentation, some of apparatus including an oscilloscope are beginning to employ the capability for self-diagnosing their electric or electronic circuitry.
However, a limitation with the above-mentioned practice as performed on some instruments is that self diagnosis is adapted to apply only to electric or electronic portions of each instrument. Therefore, the practice cannot apply to any apparatus that contain mechanical portions to be subjected to self diagnosis. Such apparatus include a data recorder comprising a video tape recorder, for example.
Unlike an electric or electronic circuit, a mechanical portion of an apparatus cannot be definitely defined in terms of input and output. With the electric or electronic circuit, it is general practice to enter a test signal in it and observe a resultant output for diagnosis. Mechanically, it is not that simple; diagnosis must often be performed on multiple complicatedly interlaced portions.
At a laboratory level, a troubleshooting expert system is under development for inferring from a symptom a failing location based on an artificial intelligence (AI) approach. Implementing such expert system requires the use of a powerful computer system such as a workstation. Such implementation is unrealistic in terms of cost for the present invention which intends to incorporate the self diagnostic capability in an apparatus. In addition, the construction of an expert system requires a large-scale database on which inference must be made from a symptom as wisely as a human expert. However, it is often difficult to prepare and install such a database on an apparatus under fabrication in which a self diagnostic capability is incorporated.
Thus, for the self diagnosis of such apparatus as a data recorder, a system must be constructed which, still supporting a conventional diagnostic capability for error detection, provides a positive troubleshooting capability such as a dedicated self diagnostic mode. Further, the above-mentioned diagnostic system must be able to cope with such a complicated symptomatic situation for diagnosing a mechanical portion of the apparatus as that, while checking portion A, an abnormal condition has been unexpectedly detected in portion B. It is also desirable for the built-in diagnostic system to be implemented by a simple approach rather than complicated one typically supported by AI.